Battery charger

ABSTRACT

A battery charger which includes an input supply terminal configured to receive a supply signal, a battery terminal configured to be connected to a battery, at least one output terminal and an electrical path between the battery terminal and the output terminal, at least one device for the detection of one alarm condition of the battery or the battery charger. The battery charger includes circuitry configured to enable the at least one detection device at timing intervals when the battery supplies the at least one output terminal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Italian patentapplication serial number MI2012A000332,filed on Mar. 2, 2012, which ishereby incorporated by reference to the maximum extent allowable by law.

BACKGROUND

1. Technical Field

The present invention relates to a battery charger.

2. Discussion of the Related Art

Nowadays mobile phones, digital cameras, notebooks, netbooks, tabletsetc. have become daily used electronic devices. The power of thebatteries of these electronic devices determines a length of time of useof the electronic device. Electronic devices such as mobile phones,digital cameras, notebooks, netbooks, tablets etc. should be used withcorresponding battery chargers. Generally, these battery chargers (orcalled as power supplies) are unique to the corresponding electronicdevices.

Typically, each battery charger is provided with an input terminal, suchas a USB terminal, for connection to the power line for charging thebattery and simultaneously powering the device connected to the battery,as shown in FIG. 1.

The battery charger 20 in FIG. 1 comprises the USB input terminal IN, acontrol block 10 configured to control first M1 and second M2transistors arranged in the path between the input terminal IN and theoutput terminals SYS and Ld and third M3 and fourth M4 transistorsarranged in the path between the input terminal IN and the battery BATdownstream the transistors M1, M2. When a supply voltage is present atthe input terminal IN, the control block 10 turns on the transistorsM1-M4 to provide power to the loads connected to the terminals SYS andLd and to charge the battery BAT. When the supply voltage is not presentat the input terminal IN, the control block 10 turns on the transistorsM3-M4 and turns off M1-M2 so the power deriving from the battery BATsupplies the loads connected to the terminals SYS and Ld and the batterycharger itself.

The control block receives an enable signal CEN an a shut-down signal SDand comprises a current modulation block adapted to control thetransistor M4. Also the control block 10 is able to send an enablesignal EN to a LDO block configured to supply an external load with aconstant voltage by means of the output terminal Ld.

Also the battery charger comprises some protection circuits to operatethe battery disconnection when a protection parameter such as the overdischarge current (OCD) or the over discharge voltage (OVD) happens. Forthe continuous monitoring of the protection parameters the batterycharger may consume a certain quantity of current, for example up to 15microampere, which can be considered high in the case wherein a load,for example a microcontroller, connected with the battery charger hasthe same current consumption.

SUMMARY

In view of the state of the art, embodiments provide a battery chargerdevice provided with a parameter monitoring system that reduces thecurrent consumption.

According to an embodiment, there is provided a battery chargercomprising an input supply terminal configured to receive a supplysignal, a battery terminal configured to be connected to a battery, atleast one output terminal and an electrical path between the batteryterminal and the output terminal, at least one device for the detectionof one alarm condition of the battery or the battery charger, comprisingcircuitry configured to enable said at least one detection device attiming intervals when the battery supplies the at least one outputterminal.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the embodiments will become apparent fromthe following detailed description of an embodiment thereof, illustratedonly by way of non-limitative example in the annexed drawings, in which:

FIG. 1 shows a battery charger according to prior art;

FIG. 2 shows a battery charger according to an embodiment;

FIG. 3 shows a part of the battery charger in FIG. 2 and time diagramsof some signals in play; and

FIG. 4 shows a block diagram of the operation method of the batterycharger according to embodiment.

DETAILED DESCRIPTION

A battery charger device according to an embodiment is shown in FIG. 2.

The battery charger comprises an input supply terminal IS, for example aUSB terminal, configured to receive a supply signal Vdd, a batteryterminal BT configured to be connected to a battery 100, at least oneoutput terminal SYS, Ld for the connection with an external device, anelectrical path 11 between the input supply terminal IS and at least oneoutput terminal SYS, Ld and another electrical path 12 between thebattery terminal BT and at least one output terminal SYS, Ld.

Preferably the battery charger comprises two switches M1 and M2 arrangedin the electrical path 11 between the input supply terminal IS and atleast one output terminal SYS, Ld. Preferably the battery chargercomprises two output terminals SYS and Ld and a block LDO that isconnected to the electrical path 11, downstream the switches M1 and M2,an provides to supply the output terminal Ld with a constant voltage andcurrent. The switches M1 and M2 are controlled by a control circuitblock 40.

The battery charger comprises another couples of switches M3 and M4arranged in the electrical path 11 between the output terminals SYS, Ldand the battery terminal BT. The switches M3 and M4, for example PMOStransistors, are controlled by another control circuit block 45. Thecontrol circuit blocks 45 and 40 are coupled with the power pathcontroller 55 configured to control when the output terminal SYS, Ldmust be supplied from the external supply Vdd, by means of the terminalIS, or from the battery 100.

The battery charger comprises means configured to detect malfunctioningor alarm conditions of the battery or the battery charger, for examplean over current discharge (OCD) condition or an over voltage discharge(OVD) condition of the battery or the absence of the supply voltage Vddat the input supply terminal IS.

The battery charger comprises at least one device Comp1, Comp2 . . .Compn configured to detect an alarm condition of the battery 100 or thebattery charger. In one embodiment, the battery charger comprises aplurality of detection devices Comp1, Comp2 . . . Compn for detect aplurality of alarm conditions; said plurality of detection devicesComp1, Comp2 . . . Compn are preferably comparators, configured tocompare parameters of the battery and the battery charger with referencesignals to detect the malfunctioning or alarm conditions. As shown inFIG. 2, when the battery supplies the block LDO and the output terminalSYS, the comparator Comp1 is configured to detect the OCD condition bycomparing a current signal BC of the battery 100 with a referencecurrent Ref1, the comparator Comp2 is configured to detect the OVDcondition by comparing a voltage signal BV of the battery 100 with areference voltage Ref2, the comparator Compn is configured to detect thepresence or absence of the supply voltage Vdd at the input supplyterminal IS by comparing the signal Dect-Vdd at the input supplyterminal IS with a reference voltage Refn

A control circuit 50, which receives a clock signal CLK deriving from anoscillator 51, is configured to enable said at least one detectiondevice at timing intervals Ten, preferably at regular timing intervalsTen. The control circuit 50 sends enable signals En1, En2 . . . Enn tothe comparators Comp1, Comp2 . . . Compn when the battery 100 suppliesthe output terminal SYS, Ld. The supply of the output terminal SYS, Ldfrom the battery 100 is detected by the power path controller 55 whichsends an enable signal GO_COMP to the control circuit 50. The enablingsignals En1, En2 . . . Enn are signals adapted to enable each comparatorComp1, Comp2 . . . Compn for an enable time period Ten cyclically foreach time period T; particularly each comparator Comp1, Comp2 . . .Compn is enabled from the control circuit 50 for the time period Ten andis disabled for a time period Tf for each time period T=Tf+Ten. Ifduring the time period Ten a signal among the signals BC, BV, . . .Dect-Vdd is higher than the respective reference signals Ref1, Ref2 . .. Refn, the respective comparator Comp1, Comp2 . . . Compn outputs ahigh level logic signal C1, C2 . . . Cn and the control circuit 50receives the high level logic signal C1, C2 . . . Cn. Normally the timeperiod Ten is constant but, if the control circuit 50 receives a highlevel logic signal C1, C2 . . . Cn, it enables said comparator for alonger time period Ten, wherein the new time period Ten has a variableduration; if the logic signal C1, C2 . . . Cn passes from the high levelto the low level within the time period Ten when the time period Ten isshorter than a prefixed time period td_(—)1, td_(—)2 . . . td_n, noalarm signal AL1, AL2, . . . ALn is sent at the output otherwise, whenthe time period Ten is equal to the prefixed time period td_(—)1,td_(—)2 . . . td_n, an element of the elements D1, D2 . . . Dn, havingat the input the signals C1, C2 . . . Cn, transfers the signal to analarm device 52 able to emit the alarm signal AL1, AL2 . . . ALn. If thelogic signal C1, C2 . . . Cn is kept at high level for a time periodequal to the prefixed time period td_(—)1, td_(—)2 . . . td_n, the logicsignal C1, C2 . . . Cn is a real alarm and not a false one, that is nota disturb.

The battery charger according to an embodiment has a current consumptionlower than the known ones. Particularly a reduction of about 70% isachieved with the battery charger in FIG. 2.

Preferably the enable time periods Ten for all the comparators Comp1,Comp2 . . . Compn occur at the same time instant Tc1; . . .

Preferably the enable time periods Ten are equal for all the comparatorsComp1, Comp2 . . . Compn

As shown in more detail in FIG. 3, with reference to the comparatorCompn, the control circuit 50 sends the enable signal Enn to thecomparator Compn, when the battery 100 supplies the output terminal SYS,Ld. The enable signal Enn enables the comparator Compn for a time periodTen and disables it for a time interval Tf cyclically for each timeperiod T with T=Ten+Tf. If during the time period Ten the signalDect-Vdd is higher than the reference signal Refn, the comparator Compnoutputs a high level logic signal Cn. The control circuit 50, whichreceives the signal Cn, enables said comparator for a longer time periodTen; if the logic signal Cn passes from the high level to the low levelwithin the time period Ten when the time period Ten is shorter than aprefixed time period td_n, no alarm signal ALn is sent at the outputotherwise, when the time period Ten is equal to the time period td_n,the element Dn, having the signal Cn at the input, transfers the signalCn to alarm device 52 able to emit the alarm signal ALn.

The battery charger according to an embodiment operates according to thefollowing method, as shown in FIG. 4.

The method comprises a step A1 for enabling at least one detectiondevice at timing intervals Ten, preferably at regular timing intervals,when the battery 100 supplies the at least one output terminal SYS, Ld.Preferably said enabling step comprises enabling the at least onedetection device for an enable time period Ten for each time period T.That is, when the battery 100 supplies the output terminals SYS, Ld andthe signal GO_COMP is received by the control circuit 50, the samecontrol circuit 50 is able to enable the at least detection device attiming intervals Ten, preferably at regular timing intervals. Preferablythe control circuit 50 sends enable signals En1, En2 . . . Enn to thedetection devices, that is the comparators Comp1, Comp2 . . . Compn. Inthis way the comparators Comp1, Comp2 . . . Compn are enabled for a timeperiod Ten and output signals C1, C2 . . . Cn in response to thecomparison between the signals BV, BC, . . . Dect-Vdd with the referencesignals Ref1, Ref2,. . . Refn.

The operation method comprises a step A2 for verifying, after theenabling step A1, if an alarm condition is detected and a step A3 forenabling, if the verify operation is positive (Yes), said at least onedevice for a longer time period Ten, or a step A10 for disabling, if theverify operation is negative (No) said at least one detection device fora disable time period Tf between an enable time period Ten and thesuccessive one. In the step A3 the control circuit 50, which isconfigured to receive the signals C1, C2 . . . Cn, receives one logicsignal C1, C2 . . . Cn, that is one of the logic signals is at a highlevel and enables the respective comparator for a longer time periodTen.

After the step A3, a step A4 occurs to verify if said alarm condition isdetected for a time period Ten equal to a prefixed time period td_(—)1,td_(—)2 . . . td_n, that is if said one logic signal C1, C2 . . . Cn iskept at the high logic level for a time period equal to a prefixed timeperiod td_(—)1, td_(—)2 . . . td_n.

If the verify operation of the step A4 is positive (Yes) a further stepAS occurs for emitting an alarm signal AL1, AL2, . . . ALn otherwise(No), when the time period Ten is shorter than a prefixed time periodtd_(—)1, td_(—)2 . . . td_n, no alarm signal is emitted and thedetection device is disabled by passing from the step A4 to the stepA10.

Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description is by wayof example only and is not intended as limiting. The invention islimited only as defined in the following claims and the equivalentsthereto.

What is claimed is:
 1. Battery charger comprising an input supply terminal configured to receive a supply signal, a battery terminal configured to be connected to a battery, at least one output terminal and an electrical path between the battery terminal and the output terminal, at least one device for the detection of one alarm condition of the battery or the battery charger, and circuitry configured to enable said at least one detection device at timing intervals when the battery supplies the at least one output terminal.
 2. Battery charger according to claim 1, wherein said circuitry is configured to enable said at least one detection device at regular timing intervals (Ten) when the battery supplies the at least one output terminal.
 3. Battery charger according to claim 1, wherein said circuitry is configured to enable said at least one detection device for an enable time period and disable said at least one detection device for a disable time period between an enable time period and the successive one, said enable means being configured to enable said at least one detection device for a longer time period if an alarm condition is detected.
 4. Battery charger according to claim 3, wherein said at least one detection device comprises an alarm means configured to emit an alarm signal if the alarm condition is detected for an enable time period equal to a prefixed time period.
 5. Battery charger according to claim 4, wherein said at least one detection device comprises a comparator configured to compare a parameter signal representative of a parameter of the battery or the battery charger and a reference signal, said circuitry is configured to enable said comparator for said enable time period, to verify if said parameter signal is higher than the reference signal and to increase the enable time period only if said parameter signal is higher than the reference signal, said alarm means being configured to emit an alarm signal if said parameter signal is kept higher than the reference signal for an enable time period equal to a prefixed time period.
 6. Battery charger according to claim 1, wherein said alarm condition is an over current discharge condition or an over voltage discharge condition of the battery.
 7. Battery charger according to claim 1, wherein said alarm condition is a presence of a supply signal at the input supply terminal
 8. Battery charger according to claim 1, comprising a plurality of detection devices, said circuitry being configured to enable all the detection devices for enable time periods at the same time instant.
 9. Battery pack comprising a battery (100) and a battery charger as defined in claim
 1. 10. A method of operating a battery charger, said battery charger comprising an input supply terminal configured to receive a supply signal, a battery terminal configured to be connected to a battery, at least one output terminal and an electrical path between the battery terminal and the output terminal, at least one device for the detection of one alarm condition of the battery or the battery charger, comprising enabling said at least one detection device at timing intervals when the battery supplies the at least one output terminal.
 11. The method according to claim 9, wherein said enabling step comprises enabling said at least one detection device at regular timing intervals.
 12. The method according to claim 10, wherein said enabling step comprises enabling said at least one detection device for an enable time period, said operation method comprising: verifying, after the enabling step, if an alarm condition is detected, enabling, if the verify operation is positive, said at least one device for a longer enable time period or, if the verify operation is negative, disabling said at least one detection device for a disable time period between an enable time period and the successive one, verifying, only after the step of enabling said at least one device for a longer enable time period, if said alarm condition is detected for a enable time period equal to a prefixed time period, emitting an alarm signal if the verify operation of the preceding step is positive. 